The Hazorites attack, and god helps Joshua to kill them and their horses, and to burn their chariots. Then he goes back to their city, kills the king and all the inhabitants, and burns it to the ground.
This is what Jerry Falwell has to say about that: Archaeological excavations at Hazor have yielded destruction layers at three levels: around 1400 BC, around 1300 BC, and around 1230 BC. Because the later two dates are probably to be associated wit the campaigns of Egyptian Pharaohs of the Nineteenth Dynasty, the 1400 BC date must reflect Joshua's campaign, a date that further supports the biblical chronology favoring an early Exodus. Oh, I see Jerry. You find evidence of a city that was destroyed three times and choose the date that is most convenient for your narrative, and ignore the evidence that other cities Joshua 'destroyed' namely Jericho and Ai, were in fact demolished a thousand years before your time frame. That's some fine sleuthing.
Anyway, Joshua then goes along and wrecks some other kingdoms, but doesn't burn them down because he's so merciful and shit. They do, of course, loot the cities, though apparently it all goes to god.
The war goes on for a long time, and no nation save the Gibeonites makes a peace treaty, mostly because god hardens their hearts, just like he did with Pharaoh. Just to spell this out: god hardens their hearts so they won't make a treaty, then punishes them for not making treaties. It's like dealing with an angry toddler. Finally, they drive the giants out and rest.
A list of the 31 nations that Joshua destroyed, though only the names of the kings are listed. This is such a feel-good book. It makes me long for Chicken Soup for the Soul.